Persecuted Rohingya trafficked through deadly jungle camps have been sold to Thai fishing vessels as slaves to produce seafood sold across the world, the Guardian has established.

So profitable is the trade in slaves that some local fishermen in Thailand have been converting their boats to carry Rohingyas instead of fish.

Sold from a jungle camp to Thailand’s fishing industry: ‘I saw 13 people die’

A Guardian investigation into Thailand’s export-orientated seafood business and the vast transnational trafficking syndicates that had, until recently, been holding thousands of Rohingyas captive in jungle camps, has exposed strong and lucrative links between the two.

Testimony from survivors, brokers and human rights groups indicate that hundreds of Rohingya men were sold from the network of trafficking camps recently discovered in southern Thailand.

According to those sold from the camps on to the boats, this was frequently done with the knowledge and complicity of some Thai state officials. In some cases, Rohingyas held in immigration detention centres in Thailand were taken by staff to brokers and then sold on to Thai fishing boats.

Other Rohingyas say Thai officials collected them from human traffickers when they arrived on the country’s shores and transported them to jungle camps where they were held to ransom or sold to fishing boats as slave labour.

Thailand’s seafood industry is worth an estimated $7.3bn a year. The vast majority of its produce is exported. Last year, another Guardian investigation tracked the supply chain of prawns produced with slave labour to British and American supermarket chains.

Though the Guardian has not irrefutably linked individual Thai ships using Rohingya slaves to specific seafood supermarket produce, the likelihood is that some seafood produced using this labour will have ended up on western shelves.

The scale of the profitable and sophisticated human trafficking networks making money from the desperation of hundreds of thousands of persecuted Rohingya “boat people” has been emerging over the past weeks.

Tens of thousands of Rohingya fled state-sponsored ethnic cleansing in Burma in the first three months of this year. Stateless and unwanted, their only option was to take to the seas in their desperate attempt to reach the relative safety of Malaysia.

In March, the special rapporteur on human rights in Burma, Yanghee Lee, told the UN Human Rights Council that Rohingya people in camps for internally displaced people had only two options: “stay and die” or “leave by boat”.

The plight of the victims recently attracted international attention following the discovery of several abandoned vessels containing hundreds of starving Bangladeshi migrants and persecuted Rohingya, which Thailand, Malaysia and Indonesia all initially refused to allow ashore.

In May, officials in Thailand and Malaysia also discovered a number of jungle prisons and mass graves used as holding pens for the traffickers’ operations.

These jungle camps were used as open-air prisons in which the inmates were held captive while they were ransomed to their relatives for sums often exceeding a thousand pounds. Many of those held in the camps were raped, tortured or beaten to death.

Camp survivors and brokers, all of whom spoke on condition of anonymity, said that those who could not raise the money demanded by their captors would be sold into slavery in return for a fee paid by the boat captains. Their testimonies corroborate the accounts of rights groups investigating Rohingya trafficking.

A young Rohingya described how he was sold by traffickers from the jungle camps on to a boat carrying the Thai national flag in Songkhla, southern Thailand, before escaping at the end of last year.

“We were taken [from the camps] by boats and cars, we arrived in Songkhla and were put on to the fishing ship,” he says. “We were forced to work there. We had to work on the sea for about four years. During this time the ship never came back to shore.”

Matthew Smith, executive director of Bangkok-based Fortify Rights, said the link between the camps and the fishing industry was well-established and had a long history. “When men or boys [held in traffickers’ camps] are unable to pay … to secure their freedom they are often sold to fishing boats for use in slave labour. This has been happening for decades. It’s a situation in the Thai fishing sector that’s been going on since the 90s, at least as far as we can tell,” he said.

A broker interviewed in Bangkok acknowledged the use of Rohingya slaves in the fishing trade, recounting how he had sold around 100 people from the jungle camps over the past year, some as recently as early this year, making around 30,000 Thai baht ($900) per sale.

“They [the migrants] were bought by the Thai boat captains,” he said, adding, “they could never leave the boats because they might run away, and then [the captains] would lose their labour. I’ve heard that if they can’t work [the captains] throw them into the sea.” In addition to Rohingya, he sold Laotian, Burmese and Cambodian migrants as slave labour to the ships.

Despite a crackdown on the use of slave labour by the Thai government, evidence suggests that the sale of Rohingya kept in jungle camps was happening as recently as early this year.

Thailand is facing unprecedented pressure to tackle human trafficking and clean up its fishing industry. This April the EU gave Thailand six months to crack down on illegal fishing and labour abuses or face a trade ban, which could see Thailand lose up to €1bn a year in seafood exports.

In recent months, Thailand has claimed to have taken decisive action, shutting down all active Rohingya trafficking camps and pushing through a series of hasty reforms in its seafood sector, including requiring boat owners to register migrant workers and undergo new licensing and registration of all boats and equipment to try and stave off the EU ban.

“The government does not mean to hurt anyone. But we have to adjust the country’s fishing system,” said Minister Peetipong Phuengbun, agriculture and cooperatives minister, last week.

Seafood prices are reported to be rising across the country and according to the Thai Overseas Fisheries Association, about 3,000 fishing ships will not go to sea because of fears of fines imposed for not complying with the new regulations. In the first week in July this year, fishermen in 22 provinces across Thailand went on strike, protesting about the hastily imposed reforms,which they say are costing the industry $444m a month.

Fishermen in Ranong say that that these reforms, coupled with decades of overfishing and ecological destruction that has pushed fish stocks to the brink, mean they are increasingly unable to make a living. Instead, they are increasingly turning to another line of business: people trafficking.

“Right now … it’s really hard to find fish in the Gulf of Thailand. When this kind of job comes along it can make me money,” said one boat owner. “The more people I bring, the more money I make … and to be honest, I want to make money. We can transport 300 to 400 people, because we have a big boat.”

Another local boat owner told the Guardian that he knew of 10 boats operating from the same port, carrying 12,000 Rohingyas a month. These migrants could be worth around $24m in ransom money.

Thailand will be hoping that its public effort to tackle its trafficking problems will earn it an upgrade in this year’s US State Department Trafficking in Persons report (TiP), which evaluates countries based on their success in combating the activities of traffickers in their jurisdiction, which is due to be published this week . In 2014, as the Guardian revealed Asian slave labour was producing prawns for supermarkets in the US and UK, Thailand was relegated to tier three, the lowest possible ranking.

Anti-trafficking groups say the changes made by the Thai authorities are insufficient to make any real difference. “Since last year’s TiP demotion, Thailand has announced tougher legislation to address trafficking, but we have seen little or no evidence of real improvement,” says Melysa Sperber, director of the Alliance to End Slavery and Trafficking, a coalition of anti-trafficking organisations.

“Our partners on the ground report that these changes are mainly cosmetic, and we shouldn’t assume that any changes made are anything more than propaganda. We continue to hear reports from our members of debt bondage, slavery and violence in Thailand’s export-orientated fishing activities.”

The Guardian made multiple attempts to contact the Thai government but received no reply.

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